This medium sized (18 inches high) cultivar originated as the result of a cross of two
seedlings of Hosta 'Brim Cup'. It was registered by
Paul Aden in
1986 and has leaves that are broadly ovate with thick substance.
It bears near white flowers in late June into July. Since it has such a wide variegated margin of white which
tends to be thin in substance, this cultivar often suffers from
rips along the leaf edge.
According to
The Hostapedia by Mark Zilis
(2009), "Like 'Brim Cup', 'Lunar
Eclipse' and a few others, 'Knockout' makes an attractive,
creamy-margined mound of foliage as an immature, juvenile plant.
With age, however, the leaf margin tends to "drop out", leaving
an unsightly sawtooth edge. Avoid this cultivar."
Similar cultivars include H.
'Brim Cup' and H. 'Snow
Cap'.
